The effect of kallikrein on human sperm membrane function

Effects of hypercholesterolaemia on Leydig and Sertoli cell secretory function and the overall sperm fertilizing capacity in the rabbit

The effects of hypercholesterolaemia on testicular endocrine and exocrine function were evaluated. The influence of hypercholesterolaemia on sperm quality, quantity, and fertilizing potential was also determined. Ten mature rabbits (group A) were fed chow containing 3% cholesterol for 12 weeks. Ten control rabbits (group B) were fed normal chow for the same period. At the end of the experimental period testosterone profiles and sperm parameters were evaluated and the sperm reproductive potential was assessed by in vitro fertilization (IVF) techniques. Peripheral serum testosterone responses to testicular stimulation with human chorionic gonadotrophin, androgen-binding protein activity in testicular cytosols, sperm concentration, sperm motility, length of sperm midpiece, and IVF outcome were all significantly lower in group A than in group B. In contrast, serum cholesterol concentrations were significantly higher in group A. There were no significant differences in either testicular versus intra-abdominal temperature differences or cholesterol concentrations in seminal plasma or testicular tissue between groups A and B. The results suggest that hypercholesterolaemia has a detrimental effect on Leydig and Sertoli cell secretory function, spermatogenesis, epididymal sperm maturation process, and the overall sperm fertilizing capacity.

The hypoosmotic swelling test: Its employment as an assay to evaluate the functional integrity of the frozen-thawed bovine sperm membrane

The objective of this study was to determine the effectiveness of the hypoosmotic swelling (HOS) test together with the supravital test as a means of evaluating the functional integrity of frozen-thawed bovine sperm membrane. A solution consisting of equal parts of fructose and sodium citrate was prepared and the osmolality varied from 50 to 300 mOsm/L. From these various solutions under study, the 100 mOsm/L solution resulted in a maximal number of clearly identifiable swollen spermatozoa. The results from the supravital test indicated that the HOS solution preserved the integrity and prevented excessive lysis of the sperm membrane during the assay. A good correlation was found between the percentage of motile spermatozoa and spermatozoa that reacted to the HOS test (r = 0.73) and between the percentage of sperm with intact membranes and HOS reactive sperm (r = 0.81). Spermatozoa showing swelling of the entire tail region accounted for more than 60% of the total swelling for the HOS solution at 100 mOsm/L. The results obtained in this study indicate that frozen-thawed bovine spermatozoa did react to the HOS test. This technique could prove useful in studies involving the function of the sperm membrane and could possibly predict the sperm's ability to fertilize.

Confocal scanning laser microscopy of morphometric human sperm parameters: correlation with acrosin profiles and fertilizing capacity

OBJECTIVES

To develop quantitative criteria for assessing sperm morphology and to determine the correlation between the percentage of morphologically normal spermatozoa and the outcome of the sperm hypo-osmotic swelling test, sperm acrosin profile, and sperm capacity for fertilization.

DESIGN

The maximal length and width of the sperm head, the length of the midpiece and principal piece of the sperm tail, and the ratio of the surface of the acrosomal region to the total surface of the head were determined in specimens obtained from a group of infertile men and a group of fertile men using a confocal scanning laser microscope. Group A consisted of 53 infertile men who were participating in an IVF program, and group B consisted of 98 fertile men. The mean +/- 2 SD of the morphometric parameters in group B was established as representing the lowest and highest normal values in both groups. A normal spermatozoon was defined as one with morphometric parameters within normal levels. The lowest percentage of morphologically normal spermatozoa, hypo-osmotic swelling test result, and acrosin activity in group B were also taken as the lowest normal values in group A.

SETTING

In vitro fertilization program at the Tottori University School of Medicine, Yonago, Japan.

MAIN OUTCOME MEASURES

Sperm morphometric parameters, percentage of morphologically normal spermatozoa, hypo-osmotic swelling test, and acrosin activity.

RESULTS

The length of the midpiece, ratio (x 100) of the surface of the acrosomal region to the total surface of the sperm head, percentage of morphologically normal spermatozoa, outcome of hypo-osmotic swelling test, and acrosin activity were significantly higher in group B than in group A. The maximal width of the head was significantly lower in group B than in group A. Strongly positive correlations were observed between percentage of morphologically normal spermatozoa or length of midpiece and the proportion of fertilized oocytes in group A and between ratio (x 100) of the surface of the acrosomal region to the total surface of the head and acrosin activity in groups A and B. Sperm morphology showed high positive and negative predictive values for acrosin activity (normal/abnormal) and fertility potential (present/absent).

CONCLUSIONS

Using quantitative strict criteria, we found that sperm morphology was an important predictor of sperm fertilizing capacity. The confocal scanning laser microscope provided useful information about the sperm cytoskeleton and its importance in fertilization.

The importance of the hypoosmotic swelling test and acrosin activity assay for identifying subpopulations of idiopathic infertile men

Semen samples collected from fertile donors (n = 13) and pooled samples from idiopathic infertile men (n = 19) were used in this study. Measurements of the total sperm acrosin activity and the hypoosmotic swelling test (HOST) were performed in all the samples. The percentage of swollen spermatozoa and acrosin profiles were significantly lower in the infertile men than in the fertile donors. Considering the lowest values of the outcome of the HOST and the acrosin activity assay in the group of fertile men as the lowest normal values, it was proven that HOST and acrosin activity assay could identify subpopulations of infertile men of 37 and 26%, respectively. The results tend to support the employment of the HOST and the acrosin activity assay in the evaluation of idiopathic infertile men.